1. Field of the Invention
The present invention relates to a semiconductor device manufacturing system.
2. Description of the Related Art
In a method for manufacturing semiconductor devices (wafers), when a new process condition is introduced or a new equipment is introduced, some wafers of a lot are subjected to new process conditions or new equipment, while other wafers of this lot are subjected to the old processes or old equipment. For example, when new ion implantation equipment is introduced, the new ion implantation equipment is used on 10 wafers of a lot, while the old ion implantation equipment is used on 40 wafers of this lot. Thus, branching and merging of wafers are required.
In a prior art method for branching and merging wafers of a lot, the operator searches wafer numbers and branches some of the wafers manually by using vacuum tweezers. Then, the operator sets a new process in the semiconductor device manufacturing equipment in accordance with a manuscript or the like to perform the new process upon the branched wafers. Then, the operator merges the branched wafers with the other wafers by using the vacuum tweezers.
In the above-mentioned prior art wafer branching and merging method, however, since the operation therefor is manually carried out, a long operating time is required. Also, since the operation is carried out by using the vacuum tweezers, the wafers may be damaged which reduces the manufacturing yield. Further, since the operation is carried out by using a manuscript or the like, the operation may become inaccurate and be carried out incorrectly.